Electronic phase shifting system



Nov, 11, 1952 Filed Feb. 25, 1951 J. J. COUGHLlN ELECTRONIC PHASE SHIFTING SYSTEM heets-sheet 1 REM/YP Irif/65,178 I INVENTOR mlm Nav. '11,1952k J. J. COUGHLIN ELECTRONC PHASE SHIFTING SYSTEM Filed Feb. 25, 1951 3 Sheets-Sheet 5 INVENTOR Patented Nov. 11, 1952 UNITEDl STATES PATENT OFFICE V2,617,932 ELECTRONIC PHASE SHIFTING SYSTEM Joseph J. Coughlin, Rochelle Park, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application February 23, 1951, Serial No. 212,269

(Cl. Z50-27) 7 Claims.

In yaccordance with the invention, two spaceV discharge devices have a `common anode resistor but diiTerent control electrode inputs driven by local trigger circuits. A square wave source is .provided which causes operation of a local timing generator. The square Wave is blanked by causing conduction of either of the space discharge devices. Blanking performs two functions -in apparatus embodying the invention. It blanks out the square wave for the required interval or interv-als;` and it alters the Wave shape ofY the wave from the square wave source. The results in the subtraction or addition of pulses during the correction interval.

An object of the present invention is to provide a novel phase shifter for maintaining the local synchronization with incoming signals which do not have transmitted sync pulses.

A further object is to provide novel means for shaping and differentiating the wave from a signal generator, such as :a limiting amplifier or counter circuit.

lOther objects and advantages of the invention will, ofcourse, become apparent and immediately suggest themselves to those skilled in the art to which this inventionis directed from a reading of the following specification in Aconnection with the 'accompanying drawingin which.:

Fig. 1 is a schematic showing of phase shifting apparatus embodying the present invention;

Fig. 2 shows curves illustrating operation of the apparatus of Fig. lwhen correction or phase shift is not required;

Fig. 3 shows curves illust-rating operation of the apparatus when yadvance correction is effective;

Fig. 4 is similar to Fig. 3 and shows curves illustrating operation of the apparatus when correction takes place on the other phase of the square wave; and

Figs. 5 and 6 are similar in their showing to Figs. 3 and 4 but illustrate operation of the apparatus when retard Icorrection is effective.

' Fig. 1 of the -drawing shows, illustratively, apparatus embodying the invention for shifting the phase of a timing generator I0 which may be operative to -control or time equipment (not shown) such as a telegraph system or the like.

The controlled equipment is to operate, in the illustrative example, in synchronism with re- 2 ceived signals of such character that they vdo not have separate sync signals. Close synchronism is maintained by a square wave generator |2 of any known kind or type which converts the output of a standard frequency source, for example,-

applied at terminals IE and I8, to the wave form 2| shown in Fig. 2a. The standard frequency source may be of any known type. It may be a tuning fork or crystal controlled compensated oscillator which generates waves of sinusoidal form. The square Wave generator may be an amplitude limiting amplier or it may be a wellknown multivibrator triggered from the wave or pulses derived from the standard frequency source. An amplifier of the kind mentioned is `disclosed in Artzt Patent No. 2,383,360 granted August 21, 1945.

The square vwave output 2| from the square wave generator or limiter |2 is applied through a coupling condenser 24 to the grid 25 of a tube 2S. supply `and bias source (not shown) is provided for the apparatus of Fig. 1. 'Since operating and bias potential sources for the apparatus of Fig. 1 is not a distinct part of the present invention, they are not shown in detail. The anode 21 of the tube 26 is connected through a load resistor 28 to the positive terminal of the supply source as indicated schematically by terminal 29. The cathode 32 of the tube 26 is returned to a point in the system which is negative with respect to ground as indicated by the legend -B. Ground is assumed to bethe reference point for the system.

The anode 36 of the tube 38 is directly con-i nected to the anode 21 of the tube 26'.' The cathode ofthe tube 38 .is returned to ground through a cathode resistorlll. Two tubes 44 and 46 have their anodes connected through a common plate load resistor 48 to the source of positive potential as indicated schematically by the terminal 5|. The grid 53 of the tube 38 is connected to the an-odes of the tubes 44 and 46. The grid 56 of the tube 44 is connected through a series resistor 5B and a resistor 59 t-o a point of negative biasing potentialas indicated schematically at the terminal 6|. Similar resistors '63 and 64 serve the same purpose for the grid 6E of the tube 46. The source of biasing potential at the terminal 6| is suiciently mally to cut olf the tubes 44 and 46.

The voltage appearing across the resistor 4| is coupled by way of a condenser 68 to the input circuit of the timing generator l0. The condenser 68 in conjunction with a resistor 1| serves It will be understood that a suitable voltage' negative norstages intercoupled to provide a Icounting system of the type by now well known in the prior-art.

Electronic apparatus employing multiVi-brators similar to those shown illustratively in Fig. 1 of the drawing are discussed in1anarticle `entitled "Electronic Digital Counters by Warren H. Bliss appearing in the April 1949 issue of Electrical Engineering.

"The, Vnormally non-conducting tubes 44;: and 46 may each become, conductive under; control fof its respective trigger circuit 8| .01282. ,The trigger 8| -istheadvance trigger whichzoperateswhen the phase'of the timing generator .is tofbeadvanced. Thefretar'd trigger.82 operates whenithe phaseiof the timing generator `isi to be retarded. .Theiadvance ,trigger 8| .is shown as being in the-form of la well-known one-shot multivibrator comprising coupled tubes 84 Yand-i136. The time duration 'of the square-topped pulse produced bythe advancehtriggerill is controllable. by adjustment of the resistor`i88. Signals or pulses 'for initiating operationrof the advance trigger Circuit 48|;may be applied to the' terminal 9 I r througnr a coupling condenserv92 to the grid 94 ofthe tube :84. A similar connection for the retard trigger .'82 `is indicated-by referencecharacter' 96.

lrOperation of fthe apparatus yof- Fig.A 1 in. accordance with fthe inventionwill now .be described. Phase shifting is accomplished by .blanking out a section of the squarewaveZ before differentiation by the 'Rf-"Cscircuit ||-68. .Thetime .interval` of blanking is diferentifor advanceand retard. The blanking .process set forth hereinias afeature of the invention valters the wave: shape sofas vto always add` two pulses Vwhen `diierentiated'. Referring toFig. 11, tubes '44 "and L461are normally cut-off. `'Iheyconduct only when;the locally generated retardzoriadvanced; pulses exist. Arr-advance pulse is shown byFig. 3a .and isindicated as occupying :the time ,interval ta A retard1pulse` .is' shown Abyiway:V of -example .in Fig. 5a and is shown as occupying the time tr. Since theitubes 44` and 46 are; non-:conductingthe'grid '.ifn'fv the. tubel: is returnedgto `l-Bthrougln Vthe resistor 48. Because of the rvoltage-divider action of the resistor 48, conducting grid resistance ofthe tube 38,- and the resistorli I there is vappositive.D.-C. voltage on the cathode of the tube 38. Referringto Fig. 2a of the drawings,'this voltage is-represented bythepeaks I-IlIof the wave 2| when the voltageat the anode 36 is equal to or less Athan zero. yThe square wave generated in the tube :28g-across the; resistor 28 is applied to the anode .'36o'fthe tube V38.V When the tubef2 is nonfconducting, thegtube 38v drawsplate current, andi-conversely, when the tube 25- is conducting, thetubegfdraws no plate current. With plate current. in the tube '38, '.the -cathode voltage increases in a positivedirection to the peaks |03 ofthe wave 2|. The output of the tube :38 is dierentiated asy indicated inFig. 2b and the resulting `pulses are applied ',-to the local timing generator I0. 'This is done intheillustrative'example by means of coupling condensers |06 and |01: The diierentiated pulses are of considerable amplitude and thereby both the positive and negative dierentiated pulses are effective to operate the timing generator ID. When correction is required, the advance trigger 8| or the retard trigger 82 is operated. Let it be assumed that .a pulse H191A is derived frcm..the apparatus (not'shown) to lbe controlfled"from1` the timing generator Ill. This pulse will re the advance trigger and a pulse of time duration ta (Fig. 3a)

fappears in the grid-56 of the tube 414. This causes the tube 44 to conduct. The plate voltage goes #suicien'tlyr negative to cut-o" the tube 38. This causes itscathode voltage to go to zero. The result is a 'wave shape as shown in Fig. 3a. Since Acorrection can take place on either phase of the square wave, both possibilities are shown. Fig. Scand Fig. 4a illustrate these possibilities. The differentiated pulses are shown in Fig. 3b. Fig. 3c fshows *.the Aaction '.of thel locking or .counting circuitzofthetimingfgenerator f t 0 i compared to thetnormal action without correctionwhich is shown infFig. *Bd. fForthe. locaLtiming lgenerator I0 to advance with respect to'. the lsignaLthe localradvance trigger 8| :operates forca-.timers where-ta is igreaterfthan trand' less than 2t1. In Fg.f3b;the. normal pulse, now; missing, isshown dotted while thegpulses due to the operation of the advance trigger: are designa-ted |2- and- |4. Fromthis it will ber seen that one pulse isxomitted andy twcinew ones; are. added, hence, the nal result is thezadditionnf onepulse.

@When :theclocal retard. trigger 82 .operates :or res,V it couplesaxpulse of time duration taiFig. 5a) .onto'thegridzof ythetube=4| causing this tube to conduct. ...Itsfactionis.similar to thelocalad- Vance-trigger 8 :except `that thetime. interval tr is greater than the timeinterval'ta. zFig. 5a shows the voltage on the'cathodeofthe.tube538. .'Figlb shows :the differentiated pulse output. :5c shows; the' actionof the local timing generator 0 withgcorrectionas .compared to that withoutcorrection inv Fig. 5d. iThe .time interval of the. local retardstrigger this greater than'three times t1 and. less. than four jtimestl. Fig xbnshows' that three normal pulses are missing due tothe'blanking out of the. square wave for thetime tr. `The local retardtrigger.. in: operatingL as in the :case of the local;advanceztriggeriadds twopulseshence, one pulse'isfomitted. This :causes the local' timing generator ;to :be retarded with respect to the incoming signal.

Whatl isclaimed; is

1. fPhase. shifting apparatus comprising :means to provide an alternating .current ..input:signal, means to convert said signal to. square-waveform, means for repeating said square wavexsignalsfa second-repeater, a timing generator, an 'output connection from said second repeater tosaid timing generator, a control tube, means couplingsaid control tube to said second repeater to control repeaterioperation; and timingimeans :for causing said control tube to become conductivefora `predetermined time period.

2.. Phase-shifting' apparatus Icomprising means toprovide an'alternating current input signal, meansito :convert saidA signal tozsquare wave'l form, means for v'repeatingsaid Asquare Wave signals comprisinga tube having a cathode, ananodeiand a control lelectrode, a. second lrepeater comprisinga tuberhaving a cathode, ian anode and a control'electrodaa timinggenerator, an output `connection from'the cathode of saidtsecond'repeater to said timing'generatcr, a control tube,;means coupling said control tube to the control electrode of said second repeater to control repeater operation, and a multivibrator for causing said control tube to become conductive for a predetermined time period.

3. Phase shifting apparatus comprising means to provide an alternating current input signal, means to convert said signal to square wave form, means for repeating said square wave signals comprising a tube having a cathode and a control electrode, a second repeater comprising a tube having a cathode, an anode and a control electrode, a multivibrator, an output connection from the cathode of said second repeater to said multivibrator, a control tube, means coupling said control tube to the control electrode of said second repeater to control repeater operation, and a second multivibrator of the one-shot type for causing said control tube to become conductive for a predetermined time period.

4. Phase shifting apparatus comprising means to provide an alternating current input signal, means to convert said signal to square wave form, a repeater for repeating said square wave signals comprising a tube having an anode, a cathode, and a control electrode, means to couple said control electrode to said first-named means, a resistor connecting said anode to a positive direct current source, a second tube having an anode, a cathode and a control electrode, a connection from the anode of said second tube to lthe anode of said rst tube, a pair of control tubes each of which includes an anode, a cathode and a control electrode, a resistor connecting the anodes of said control tubes to said positive direct current source, a connection from said anodes of said control tubes to the control electrode of said second tube, a trigger circuit coupled to the grid of one of said control tubes, a second trigger circuit coupled to the grid of the other control tubes, each trigger circuit having means to cause the' control tube to which it is connected to become conductive.

5. Phase shifting apparatus comprising means to provide an alternating current input signal, means to convert said signal to square Wave form, a repeater for repeating said square Wave signals comprising a tube having an anode, a cathode and a control electrode, means to couple said control electrode to said rst-named means, a resistor connecting said anode to a positive direct current source, a second tube having an anode, a cathode and a control electrode, a connection from the anode of said second tube to the anode of said first tube, a control tube including an anode, a cathode and a control electrode, a resistor connecting the anode of said control tube to said positive direct current source, a connection from said anode of said control tube to the control electrode of said second tube, a trigger circuit coupled to the grid of said control tube, said trigger circuit having means to cause said control tube to become conductive whereby to cause cutoi of said second tube and a decrease in the cathode voltage thereof, the cathodes of said first tube and said pair of control tubes being connected to a voltage reference point in said system, a resistor connecting the cathode of said second tube to a voltage reference point in said circuit which is less negative than the voltage reference point of the connection of the cathode of said first-named tube.

6. Phase shifting apparatus comprising means to provide an alternating current input signal, means to convert said signal to square Wave form, a repeater for repeating said square wave signals 6 comprising a tube having an anode, a cathode, and a control electrode, means to couple said control electrode to said iirst-named means, a resistor connecting said anode to a positive direct -current source, a second tube having an anode,

a cathode and a control electrode, a connection from the anode of said second tube to the anode of said rst tube, a control tube including an anode, a cathode and a control electrode, a resistor connecting theancde ci said control tube to said positive direct current source, a connection from said anode of said control tube to the control electrode of said second tube, a trigger circuit coupled to the grid of said control tube, said trigger circuit having means to cause said control tube to become conductive whereby to cause cutoff of said second tube and a decrease in the cathode voltage thereof, the cathode of said iirst tube and said control tube being connected to a voltage reference point in said system, a resistor connecting the cathode of said second tube to a voltage reference point in said circuit which is less negative than the voltage reference point of the connection of the cathode of said iirstnamed tube, a timing generator, means for coupling the cathode of said second tube to said timing generator, means to supply a control pulse to said iirst trigger circuit, and means to supply a control pulse to said second trigger circuit.

7. Phase shifting apparatus comprising means to provide an alternating current input signal, means to convert said signal to square wave form, a repeater for repeating said square wave signals comprising a tube having an anode, a cathode, and a control electrode, means to couple said control electrode to said first-named means, a resistor connecting said anode to a positive direct current source, a second tube having an anode, a cathode and a control electrode, a connection from the anode of said second tube to the anode of said first tube, a pair of control tubes each ofl which includes an anode, a cathode and a control electrode, a resistor connecting the anodes of said control tubes to said positive direct current source, a connection from said anodes of said control tubes to the control electrode of said second tube, a trigger circuit coupled to the grid of one of said control tubes a second trigger circuit coupled to the grid of the other control tube, each trigger circuit having means to cause the control tube to which it is connected to become conductive whereby to cause cutoi of said second tube and a decrease in the cathode voltage thereof, the cathodes of said iirst tube and said pair of control tubes being connected to a voltage reference point in said system, a resistor connecting the cathode of said second tube to a voltage reference point in said circuit which is less negative than the voltage reference point of the connection of the cathode of said iirst-named tube, a timing generator, means for coupling the cathode of said second tube to said timing generator, means to supply a control pulse to said rst trigger circuit, and means to supply a control pulse to said second trigger circuit.

JOSEPH J. COUGHLIN.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 2,514,369 Buehler July 11, 1950 2,564,559 Canfora Aug. 14, 1951 

